Rare earth doped zinc oxide nanowires.

Zinc oxide (ZnO) nanowires were grown via thermal transport and subsequently doped with different concentrations of Tm, Yb, and Eu using ion implantation and post annealing. High ion fluences lead to morphology changes due to sputtering; however, freestanding nanowires become less damaged compared to those attached to substrates. No other phases like rare earth (RE) oxides were detected, no amorphization occurs in any sample, and homogeneous doping with the desired concentrations was achieved. Photoluminescence measurements demonstrate the optical activation of trivalent RE-elements and the emission of the characteristic intra-4f-luminescence of the respective RE atoms, which could be assigned according to the Dieke-diagram. An increasing RE concentration results into decreasing luminescence intensity caused by energy transfer mechanisms to non-radiative remaining implantation defect sites. Furthermore, low thermal quenching was observed due to the considerable wide band gap of ZnO.